To see, you need more than eyes. “Even when someone is losing their sight, they still have a good brain that’s trying to understand and pick up clues from objects, if given enough input,” says Stephen Hicks, research fellow in neuroscience at the University of Oxford. This mechanism means partially sighted people can be helped to see, even as their eyesight worsens. 

Read more: http://www.wired.co.uk/article/oxsight-augmented-reality-glasses-eyesight-vision-blindness